This goes back to a deep-doc subject I was working on about a month ago. At the time, none of the languages spoken today, existed back then. Adam spoke the adamic language, or the language spoken in the eternal realm. (it mentions it in the pearl, and genesis, I hit a dead end with it, so I don't have a lot to go on) From what I was able to gather from it, the adamic language was perfect, and was what we all spoke in the pre-earth life, and what we will speak when we die.
Now then, we all know that God, and Jesus Christ made the earth, but Michael, (who we know as Adam) was with them, and assisted in the creation. That could be a good explanation of why God left it up to Adam to name the animals, because he helped create them, even though Adam did not remember.
I would love to explain more, but I don't feel at liberty to discuss some things over the internet. All I shall say is... Go to the temple, and things will make sense.